Allow parsing empty RTCP TargetBitrate messages, but stop sending them.

webrtc/video/payload_router.cc

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 138 matching lines @@
     const BitrateAllocation& bitrate) {
   rtc::CritScope lock(&crit_);
   if (IsActive()) {
     if (rtp_modules_.size() == 1) {
       // If spatial scalability is enabled, it is covered by a single stream.
       rtp_modules_[0]->SetVideoBitrateAllocation(bitrate);
     } else {
       // Simulcast is in use, split the BitrateAllocation into one struct per
       // rtp stream, moving over the temporal layer allocation.
       for (size_t si = 0; si < rtp_modules_.size(); ++si) {
+        // Don't send empty TargetBitrate messages on streams not being relayed.
+        if (bitrate.GetSpatialLayerSum(si) == 0)
+          break;
+
         BitrateAllocation layer_bitrate;
         for (int tl = 0; tl < kMaxTemporalStreams; ++tl)
           layer_bitrate.SetBitrate(0, tl, bitrate.GetBitrate(si, tl));
         rtp_modules_[si]->SetVideoBitrateAllocation(layer_bitrate);
       }
     }
   }
 }
 
 }  // namespace webrtc